Electronic equipment, such as a server and an electronic computer, is installed inside buildings, such as factories and office buildings. A corrosive gas, such as hydrogen sulfide and sulfur dioxide, is often included in an environment in which electronic equipment is installed. The corrosive gas may deteriorate the performance of electronic equipment by corroding members, such as metal, forming the electronic equipment and further, may disable the operation of the electronic equipment. It is preferable to continuously monitor the corrosive gas in the environment in which the electronic equipment is installed before and after the installation of the electronic equipment in order to guarantee operation of the electronic equipment.
A QCM (Quartz Crystal Microbalance) sensor is known as a sensor for monitoring a corrosive gas. The QCM sensor is a mass sensor that has a quartz oscillator and an electrode formed on the surface of the quartz oscillator. The QCM sensor uses a phenomenon in which when the mass of the electrode increases due to corrosion, the oscillation frequency of the quartz oscillator is reduced according to the amount of corrosion. The QCM sensor is capable of detecting a change in oscillation frequency of a quartz oscillator with a very high degree of sensitivity and capable of performing measurement in a short period of time compared to that of a sensor that uses other measuring methods, such as a coupon method, and therefore the QCM sensor is adopted as an environment measuring device.